What are the raised portions between the grooves in a barrel called?

The raised portions between the grooves in a barrel are referred to as lands. In the context of firearm barrels, lands are the parts of the rifling that are not cut away, as opposed to grooves, which are the recessed areas. The lands engage the projectile as it travels down the barrel, providing spin and improving accuracy due to the stabilization of the bullet's flight. This rifling is crucial for the performance of the firearm, as it influences the bullet’s trajectory.

Understanding the role of lands is important in forensic ballistics, as the unique patterns of land and groove impressions left on a bullet can be used to identify the firearm from which it was fired. This concept is foundational in the study of ballistics and further emphasizes the importance of lands in firearm design and operation. The other options, while related to different aspects or phenomena in firearms, do not specifically define the raised areas between the grooves as clearly as the term "lands" does.